Low resistance interconnect structure for semiconductor device

ABSTRACT

The present disclosure describes an interconnect structure and a method forming the same. The interconnect structure can include a substrate, a layer of conductive material over the substrate, a metallic capping layer over the layer of conductive material, a layer of insulating material over top and side surfaces of the metallic capping layer, and a layer of trench conductor formed in the layer of insulating material and the metallic capping layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 62/949,636, titled “Low Resistance Metal Interconnect,”which was filed on Dec. 18, 2019 and is incorporated herein by referencein its entirety.

BACKGROUND

Advances in semiconductor technology have increased the demand forsemiconductor devices with higher storage capacity, faster processingsystems, higher performance, and lower costs. To meet these demands, thesemiconductor industry continues to scale down the dimensions ofsemiconductor devices, such as planar metal oxide semiconductor fieldeffect transistors (MOSFETs), fin field effect transistors (finFETs),and nano-sheet field effect transistors (NSFETs). Such scaling down hasincreased the complexity of semiconductor device manufacturingprocesses.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of this disclosure are best understood from the followingdetailed description when read with the accompanying figures.

FIG. 1A illustrates an isometric view of a semiconductor device,according to some embodiments.

FIG. 1B illustrates a cross-sectional view of a semiconductor device,according to some embodiments.

FIG. 2 is a flow diagram of a method for fabricating a semiconductordevice, according to some embodiments.

FIG. 3A illustrates an isometric view of a semiconductor device at astage of its fabrication process, according to some embodiments.

FIGS. 3B, 4-6, 7A-7C, and 8-10 illustrate cross-sectional views of asemiconductor device at various stages of its fabrication process,according to some embodiments.

Illustrative embodiments will now be described with reference to theaccompanying drawings. In the drawings, like reference numeralsgenerally indicate identical, functionally similar, and/or structurallysimilar elements.

DETAILED DESCRIPTION

It is noted that references in the specification to “one embodiment,”“an embodiment,” “an example embodiment,” “exemplary,” etc., indicatethat the embodiment described may include a particular feature,structure, or characteristic, but every embodiment may not necessarilyinclude the particular feature, structure, or characteristic. Moreover,such phrases do not necessarily refer to the same embodiment. Further,when a particular feature, structure or characteristic is described inconnection with an embodiment, it would be within the knowledge of oneskilled in the art to effect such feature, structure or characteristicin connection with other embodiments whether or not explicitlydescribed.

It is to be understood that the phraseology or terminology herein is forthe purpose of description and not of limitation, such that theterminology or phraseology of the present specification is to beinterpreted by those skilled in relevant art(s) in light of theteachings herein.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper,” and the like may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. The spatially relative termsare intended to encompass different orientations of the device in use oroperation in addition to the orientation depicted in the figures. Theapparatus may be otherwise oriented (rotated 90 degrees or at otherorientations) and the spatially relative descriptors used herein maylikewise be interpreted accordingly.

The term “nominal” as used herein refers to a desired, or target, valueof a characteristic or parameter for a component or a process operation,set during the design phase of a product or a process, together with arange of values above and/or below the desired value. The range ofvalues is typically due to slight variations in manufacturing processesor tolerances.

In some embodiments, the terms “about” and “substantially” can indicatea value of a given quantity that varies within 5% of a target value(e.g., ±1%, ±2%, ±3%, ±4%, and ±5% of the target value).

As used herein, the term “vertical,” means nominally perpendicular tothe surface of a substrate.

As used herein, the term “insulating layer”, refers to a layer thatfunctions as an electrical insulator (e.g., a dielectric layer).

As used herein, the term “selectivity” refers to the ratio of the etchrates of two materials under a same etching condition.

As used herein, the term “high-k” refers to a high dielectric constant.In the field of semiconductor device structures and manufacturingprocesses, high-k refers to a dielectric constant that is greater thanthe dielectric constant of SiO₂ (e.g., greater than 3.9).

Fins associated with fin field effect transistors (finFETs) orgate-all-around (GAA) FETs may be patterned by any suitable method. Forexample, the fins may be patterned using one or more photolithographyprocesses, including double-patterning or multi-patterning processes.Double-patterning or multi-patterning processes combine photolithographyand self-aligned processes, allowing patterns to be created that have,for example, pitches smaller than what is otherwise obtainable using asingle, direct photolithography process. For example, in someembodiments, a sacrificial layer is formed over a substrate andpatterned using a photolithography process. Spacers are formed alongsidethe patterned sacrificial layer using a self-aligned process. Thesacrificial layer is then removed, and the remaining spacers may then beused to pattern the fins.

Technology advances in the semiconductor industry drive the pursuit ofintegrated circuits (IC)s having higher device density, higherperformance, and lower cost. In the course of the IC evolution, theinterconnect structure is scaled down to achieve ICs with higher devicedensities. With the miniaturization of the interconnect structure, thecurrent density in the metal lines of the interconnect structureincreases. Such current density increasing can cause the IC failure dueto electromigration. To reconcile the electromigration, each metal lineof the interconnect structure can be covered by a metallic capping layerto reduce the migration of metallic atoms in each metal line. However,such metallic capping layer can introduce extra resistance betweendifferent layers of the interconnect structure, thus degrading theperformance of the IC.

The present disclosure is directed to a fabrication method and aninterconnect structure that provides low resistance and diminisheselectromigration. For example, the interconnect structure can include ametal wire, a metallic capping layer formed over the metal wire, and avia conductor layer formed through the metallic capping layer. Themetallic capping layer can reconcile the electromigration associatedwith the metal wire. The via conductor can contact the metal wire byremoving portions of the metallic capping layer between the metal wireand the via conductor layer. Accordingly, the contact resistance betweenthe via conductor layer and the metal wire can be reduced. In someembodiments, the interconnect structure can further include aninsulating layer formed over the metal wire and the metallic cappinglayer, where the via conductor layer can be formed through theinsulating layer and the metallic capping layer to contact the metalwire. A benefit of the present disclosure, among others, is to lower theresistance and the signal delay (e.g., RC delay) in the interconnectstructure, thus enhancing an overall performance and yield of the IC.

A semiconductor device 100 having multiple field effect transistors(FETs) 102 and one or more interconnect structure 140 (e.g.,interconnect structure 140 ₁ and 140 ₂) disposed over FETs 102 isdescribed with reference to FIGS. 1A and 1B, according to someembodiments. FIG. 1A illustrates an isometric view of semiconductordevice 100, according to some embodiments. FIG. 1B illustrates across-sectional view along line B-B of semiconductor device 100 of FIG.1A, according to some embodiments. Semiconductor device 100 can beincluded in a microprocessor, memory cell, or other integrated circuit.Though FETs 102 shown in FIGS. 1A and 1B are fin field effecttransistors (finFETs), each FET 102 can be a gate-all-around (GAA) FET,according to some embodiments.

Referring to FIG. 1A, each FET 102 can include a fin structure 108extending along an x-axis, a gate structure 112 traversing through finstructure 108 along an y-axis, and a source/drain (S/D) region 110formed over portions of fin structure 108. Although FIG. 1A shows finstructure 108 accommodating two FETs 102, any number of FETs 102 can bedisposed along fin structure 108. Each FET 102 can be formed on asubstrate 106. Substrate 106 can be a semiconductor material, such assilicon. In some embodiments, substrate 106 can include (i) anelementary semiconductor, such as silicon (Si) and germanium (Ge); (ii)a compound semiconductor including silicon carbide (SiC), galliumarsenide (GaAs), gallium phosphide (GaP), indium phosphide (InP), indiumarsenide (InAs), and indium antimonide (InSb); or (iii) a combinationthereof. Further, substrate 106 can be doped depending on designrequirements (e.g., p-type substrate or n-type substrate). In someembodiments, substrate 106 can be doped with p-type dopants (e.g., boron(B), indium (In), aluminum (Al), or gallium (Ga)) or n-type dopants(e.g., phosphorus (P) or arsenic (As)).

Semiconductor device 100 can further include shallow trench isolation(STI) regions 138 that provide electrical isolation for fin structure108. For example, STI regions 138 can electrically isolate fin structure108 from another fin structure 108 (not shown in FIG. 1A) formed insemiconductor device 100. Also, STI regions 138 can provide electricalisolation between FETs 102 and neighboring active and passive elements(not shown in FIG. 1A) integrated with or deposited on substrate 106.STI regions 138 can include one or more layers of dielectric material,such as a nitride layer, an oxide layer disposed on the nitride layer,and an insulating layer disposed on the nitride layer. In someembodiments, the insulating layer can include silicon oxide, siliconnitride, silicon oxynitride, fluorine-doped silicate glass (FSG), alow-k dielectric material, and/or other suitable insulating materials.

Referring to FIGS. 1A and 1B, fin structure 108 can include a fin baseportion 108A and a stacked fin portion 108B disposed on fin base portion108A. Fin base portion 108A can include a material identical to orsimilar to substrate 106, such as a material having a lattice constantsubstantially close to (e.g., lattice mismatch within 5%) that ofsubstrate 106. Stacked fin portion 108B can include a semiconductorlayer 122 functioning as FET 102's channel layer 122 and a S/D region110 horizontally (e.g., in the x-direction) in contact with channellayer 122.

Referring to FIG. 1B, S/D region 110 can be grown over fin base portion108A. Each of channel layers 122 of FET 102 can be interposed between apair of S/D regions 110. S/D region 110 can include an epitaxially-grownsemiconductor material. In some embodiments, the epitaxially grownsemiconductor material can be the same material as the material ofsubstrate 106. For example, the epitaxially-grown semiconductor materialcan have a lattice constant substantially close to (e.g., latticemismatch within 5%) that of the material of substrate 106. In someembodiments, the epitaxially-grown semiconductor material can include:(i) a semiconductor material, such as Ge and Si; (ii) a compoundsemiconductor material, such as GaAs and AlGaAs; or (iii) asemiconductor alloy, such as SiGe and GaAsP. S/D region 110 can be dopedwith p-type dopants or doped with n-type dopants. The p-type dopants caninclude B, In, Al, or Ga. The n-type dopants can include P or As. Insome embodiments, S/D region 110 can include a silicide layer (not shownin FIGS. 1A and 1B). The silicide layer can include metal silicide thatcan provide a low resistance interface between the underlying S/D region110 and the trench conductor layer 130.

Channel layer 122 can include semiconductor materials similar tosubstrate 106. For example, channel layer 122 can include asemiconductor material having lattice constant substantially close to(e.g., lattice mismatch within 5%) that of substrate 106. In someembodiments, channel layer 122 can include Si or SiGe. In someembodiments, channel layer 122 can include SiGe with a Ge concentrationfrom about 25 atomic percent to about 50 atomic percent with anyremaining atomic percent being Si or can include Si without anysubstantial amount of Ge. In some embodiments, channel layer 122 can beundoped, doped with p-type dopants or doped with n-type dopants. Thep-type dopant can include B, In, Al, or Ga. The n-type dopant caninclude P or As.

Gate structure 112 can be multi-layered structures that wraps aroundportions of fin structure 108. For example, gate structure 112 can wrapFET 102's channel layers 122 (e.g., semiconductor layer 122) to modulatea conductivity of FET 102's channel layer 122. In some embodiments, gatestructure 112 can be referred to as gate-all-around (GAA) structures,where FET 102 can be referred to as a GAA FET 102. Gate structure 112can include a gate dielectric layer 112A, a gate electrode 112B disposedon gate dielectric layer 112A, and gate spacers 114 disposed onsidewalls of gate electrode 112B. Gate dielectric layer 112A can bewrapped around channel layer 122, hence electrically isolating channellayer 122 from gate electrode 112B. Gate dielectric layer 112A can bedisposed between gate electrode 112B and S/D regions 110 to preventelectrical shorting in between.

Gate dielectric layer 112A can include silicon oxide and can be formedby chemical vapor deposition (CVD), atomic layer deposition (ALD),physical vapor deposition (PVD), e-beam evaporation, or other suitableprocesses. In some embodiments, gate dielectric layer 112A can include(i) a layer of silicon oxide, silicon nitride, and/or siliconoxynitride, (ii) a high-k dielectric material, such as hafnium oxide(HfO₂), titanium oxide (TiO₂), hafnium zirconium oxide (HfZrO), tantalumoxide (Ta₂O₃), hafnium silicate (HfSiO₄), zirconium oxide (ZrO₂), andzirconium silicate (ZrSiO₂), or (iii) a combination thereof. High-kdielectric layers can be formed by ALD and/or other suitable methods. Insome embodiments, gate dielectric layer 112A can include a single layeror a stack of insulating material layers. Gate dielectric layer 112A canhave a thickness ranging from about 1 nm to about 5 nm. Other materialsand formation methods for gate dielectric layers 112A are within thespirit and scope of this disclosure.

Gate electrode 112B can be a gate terminal of FET 102. Gate electrode112B can include metal stacks that can wrap about channel layer 122. Insome embodiments, gate electrode 112B can include a gate barrier layer(not shown in FIGS. 1A and 1B), a gate work function layer (not shown inFIGS. 1A and 1B), and a gate metal fill layer (not shown in FIGS. 1A and1B). The gate barrier layer can serve as a nucleation layer forsubsequent formation of a gate work function layer. The gate barrierlayer can include titanium (Ti), tantalum (Ta), titanium nitride (TiN),tantalum nitride (TaN), or other suitable diffusion barrier materials.The gate work function layer can include a single metal layer or a stackof metal layers. In some embodiments, the gate work function layer caninclude aluminum (Al), copper (Cu), tungsten (W), titanium (Ti),tantalum (Ta), titanium nitride (TiN), tantalum nitride (TaN), nickelsilicide (NiSi), cobalt silicide (CoSi), silver (Ag), tantalum carbide(TaC), tantalum silicon nitride (TaSiN), tantalum carbon nitride (TaCN),titanium aluminum (TiAl), titanium aluminum nitride (TiAlN), tungstennitride (WN), metal alloys, and/or combinations thereof. Gate metal filllayer can include a single metal layer or a stack of metal layers. Insome embodiments, the gate metal fill layer can include a suitableconductive material, such as Ti, silver (Ag), Al, titanium aluminumnitride (TiAlN), tantalum carbide (TaC), tantalum carbo-nitride (TaCN),tantalum silicon nitride (TaSiN), manganese (Mn), Zr, titanium nitride(TiN), tantalum nitride (TaN), ruthenium (Ru), molybdenum (Mo), tungstennitride (WN), copper (Cu), tungsten (W), cobalt (Co), nickel (Ni),titanium carbide (TiC), titanium aluminum carbide (TiAlC), tantalumaluminum carbide (TaAlC), metal alloys, and combinations thereof. Othermaterials for the gate barrier layer, the gate work function layer, andthe gate metal fill layer are within the spirit and scope of thisdisclosure.

Gate spacer 114 can physically contact gate dielectric layers 112A. Gatespacer 114 can include a low-k material with a dielectric constant lessthan about 3.9. For example, gate spacer 114 can include insulatingmaterial, such as silicon oxide, silicon nitride, a low-k material, anda combination thereof. In some embodiments, gate spacer 114 can have athickness ranging from about 2 nm to about 10 nm. Other materials andthicknesses for gate spacer 114 are within the spirit and scope of thisdisclosure.

Referring to FIGS. 1A and 1B, each FET 102 can further include aninterlayer dielectric (ILD) layer 118 and a padding layer 126. ILD layer118 can be disposed over fin structure 108 to provide an electricalinsulation between fin structure 108 and interconnect structure 140. Byway of example and not limitation, ILD layer 118 can include adielectric material deposited using a deposition method suitable forflowable dielectric materials (e.g., flowable silicon oxide, flowablesilicon nitride, flowable silicon oxynitride, flowable silicon carbide,or flowable silicon oxycarbide). For example, flowable silicon oxide canbe deposited using flowable CVD (FCVD). In some embodiments, thedielectric material can be silicon oxide or silicon nitride. In someembodiments, ILD layer 118 can have a thickness from about 50 nm toabout 200 nm. Other materials, thicknesses, and formation methods forILD layer 118 are within the spirit and scope of this disclosure.

Padding layer 126 can be disposed over gate structure 112 to provide anelectrical insulation between gate structure 112 and interconnectstructure 140. Padding layer 126 can be made of any suitable insulatingmaterial. By way of example and not limitation, Padding layer 126 can bemade of silicon carbide, lanthanum oxide, aluminum oxide, aluminumoxynitride, zirconium oxide, hafnium oxide, silicon nitride, silicon,zinc oxide, zirconium nitride, zirconium aluminum oxide, titanium oxide,tantalum oxide, yttrium oxide, tantalum carbide nitride, zirconiumsilicide, silicon oxynitride carbide, silicon oxycarbide, silicon carbonnitride, hafnium silicide, silicon oxide, or combination thereof. Insome embodiments, padding layer 126 can have a thickness from about 50nm to about 200 nm. Other materials, thicknesses, and formation methodsfor padding layer 126 are within the spirit and scope of thisdisclosure.

FET 102 can further include a trench conductor layer 130 formed over S/Dregion 110 and/or gate structure 112. For example, as shown in FIG. 1B,trench conductor layer 130 can be formed through ILD layer 118 andpadding layer 126 to contact the underlying S/D region 110. Therefore,trench conductor layer 130 can electrically bridge interconnectstructure 140 and the underlying S/D region 110. In some embodiments,trench conductor layer 130 can be formed through padding layer 126 tocontact with gate electrode 112B, where trench conductor layer 130 canelectrically bridge interconnect structure 140 and the underlying gateelectrode 112B. In some embodiments, trench conductor layer 130 can besubstantially coplanar with ILD layer 118 and/or padding layer 126.Trench conductor layer 130 can be made of any suitable conductivematerials, such as W, Al, Cu, Co, Ti, Ta, Ru, Mo, a silicide material,and a conductive nitride material. Trench conductor layer 130 can havean average horizontal dimension (e.g., width in the x-direction) and anaverage vertical dimension (e.g., height in the z-direction) based on apitch size of FET 102. For example, trench conductor layer 130 can havean average horizontal dimension (e.g., width in the x-direction) in arange from about 15 nm to about 25 nm and can have an average verticaldimension (e.g., height in the z-direction) in a range from about 400 nmto about 600 nm. In some embodiments, trench conductor layer 130 caninclude slanted sidewalls, such that trench conductor layer 130's topsurface's width can be greater than trench conductor layer 130's bottomsurface's width. Based on the disclosure herein, other materials anddimensions for trench conductor layer 130 are within the spirit andscope of this disclosure.

Referring to FIG. 1B, each of interconnect structure 140 (e.g.,interconnect structure 140 ₁ or 140 ₂) can be a connection networkconnecting between the underlying FETs 102 and neighboring active andpassive elements (not shown in FIGS. 1A and 1B) integrated with ordeposited on substrate 106. Although FIG. 1B shows two interconnectstructures 140 (e.g., interconnect structure 140 ₁ or 140 ₂) stacking onone another, any number of interconnect structures 140 can be includedin semiconductor device 100 to stack on one another. Interconnectstructure 140 can include a layer of conductive material 146, a layer ofinsulating material 148 disposed over layer of conductive material 146,and a trench conductor layer 162 formed through layer of insulatingmaterial 148 and in contact with layer of conductive material 146.

Layer of conductive material 146 can be a wire routing for theinterconnect structure 140. In some embodiments, layer of conductivematerial 146 can be disposed over trench conductor layer 130 toelectrically connect to FET 102's S/D region 110 and/or FET 102's gatestructure 112. In some embodiments, layer of conductive material 146 ofan interconnect structure 140 (e.g., interconnect structure 140 ₂) canbe disposed over trench conductor layer 162 of a vertically (e.g., inthe z-direction) adjacent interconnect structure 140 (e.g., interconnectstructure 140 ₁) to electrically connect to layer of conductive material146 of the vertically adjacent interconnect structure 140 (e.g.,interconnect structure 140 ₁). In some embodiments, layer of conductivematerial 146 can be a patterned layer. For example, interconnectstructure 140 can further include a layer of insulating material 144that can electrically isolate a layer of conductive material 146 fromanother layer of conductive material 146 (not shown in FIG. 1B) ininterconnect structure 140. In some embodiments, layer of insulatingmaterial 144 can be laterally (e.g., in the x-y plane) adjacent to andsubstantially coplanar with layer of conductive material 146. Layer ofconductive material 146 can include any suitable conductive material. Byway of example and not limitation, layer of conductive material 146 caninclude Cu, Co, Ni, Al, In, W, Ru, rhodium (Rh), iridium (Ir), osmium(Os), carbon nanotubes, or a combination thereof. In some embodiments,layer of conductive material 146 can further include a barrier liner(not shown in FIG. 1B), such as TiN, TaN, and a conductive nitridematerial. Other conductive materials for layer of conductive material146 are within the spirit and scope of this disclosure.

Layer of insulating material 148 can be sandwiched between layers ofconductive material 146 of two vertically (e.g., in the z-direction)adjacent interconnect structures 140 (e.g., between interconnectstructure 140 ₁ and interconnect structure 140 ₂). In some embodiments,layer of insulating material 148 can be further disposed over layer ofinsulating material 144 adjacent to layer of conductive material 146.Each of layer of insulating material 148 and layer of insulatingmaterial 144 can include any suitable insulating material. By way ofexample and not limitation, each of layer of insulating material 148 andlayer of insulating material 144 can include silicon oxide, siliconnitride, silicon oxynitride, a low-k dielectric, or a high-k dielectric.In some embodiments, layer of insulating material 148 can includemultiple dielectric layers (not shown in FIG. 1B) that have differentetching selectivity from each other. Other insulating materials forlayer of insulating material 148 and layer of insulating material 144are within the spirit and scope of this disclosure.

Trench conductor layer 162 can electrically connect layers of conductivematerial 146 between layers of conductive material 146 of two vertically(e.g., in the z-direction) adjacent interconnect structures 140 (e.g.,between interconnect structure 140 ₁ and interconnect structure 140 ₂).For example, trench conductor layer 162 can include a bottom surface 161in contact with interconnect structure 140 ₁'s layer of conductive layer146, and a top surface 165 in contact with interconnect structure 140₂'s layer of conductive layer 146. Trench conductor layer 162 caninclude any suitable conductive materials formed over layer ofconductive material 146's top surface. In some embodiments, trenchconductor layer 162 can include a metal conductor layer and a barrierlayer disposed over the metallic layer (both not shown in FIG. 1B). Byway of example and not limitation, the metal conductor layer can includeW, Al, Cu, Co, Ti, Ta, Ru, Mo, or carbon nanotube. By way of example andnot limitation, the barrier layer can include a metal (e.g., Ta ortitanium tungsten (TiW)), a metal oxide (e.g., alumina, manganese oxide,chromium oxide, niobium oxide, or titanium oxide), or a metal nitride(e.g. TaN or TiN). In some embodiments, the barrier layer can have athickness ranging from about 5 Å to about 30 Å. Trench conductor layer162 can have a horizontal dimension (e.g., width in the x-direction) anda vertical dimension (e.g., height in the z-direction) based on a pitchsize of FET 102. For example, trench conductor layer 162 can have avertical (e.g., in the z-direction) height ranging from about 5 nm toabout 1000 nm. In some embodiments, trench conductor layer 162's bottomsurface 161 can have a horizontal (e.g., in the x-direction) width W₁₆₁ranging from about 1 nm to about 80 nm. In some embodiments, trenchconductor layer 162's top surface 165 can have a horizontal (e.g., inthe x-direction) width W₁₆₅ ranging from about 1 nm to about 80 nm. Insome embodiments, trench conductor layer 162 can include slantedsidewalls, such that trench conductor layer 162's top surface's widthcan be greater than trench conductor layer 162's bottom surface's width.Based on the disclosure herein, other materials, widths, and heights fortrench conductor layer 162 are within the spirit and scope of thisdisclosure.

In some embodiments, interconnect structure 140 can further include aconductive capping layer 142 to inhibit electromigration associated withlayer of conductive material 146. For example, conductive capping layer142 can be selectively formed over layer of conductive material 146'stop surface to block the outflow or the out-diffusion of metallic atomsfrom layer of conductive material 146. Conductive capping layer 142 canbe made of any suitable barrier material that has less atomic mobility.In some embodiments, conductive capping layer 142 can be made of anysuitable conductive material that has less atomic mobility. By way ofexample and not limitation, conductive capping layer 142 can include Co,W, Ta, TiN, TaN, or Ru. As shown in FIG. 1B, conductive capping layer142 can include a top surface 145 and a sidewall 143, both in contactwith layer of insulating material 148. Conductive capping layer 142 canfurther include a bottom surface 141 in contact with layer of conductivematerial 146. In some embodiments, conductive capping layer 142 canfurther include a lower shoulder structure 154 resulting from a lateral(e.g., in the x-direction) extension of conductive capping layer 142during the growth of conductive capping layer 142. Lower shoulderstructure 154 can connect bottom surface 141 and sidewall 143 bytapering from sidewall 143 to bottom surface 141. For example, lowershoulder structure 154 can have a warped surface, a curved surface, or arounded surface that tapers from sidewall 143 towards bottom surface141. In some embodiments, conductive capping layer 142 can also includean upper shoulder structure 152 that can connect top surface 145 andsidewall 143 by tapering from sidewall 143 to top surface 145. Forexample, upper shoulder structure 152 can have a warped surface, acurved surface, or a rounded surface that tapers from sidewall 143toward top surface 145. In some embodiments, conductive capping layer142 can horizontally (e.g., in the x-direction) extend from layer ofconductive material 146 towards layer of insulating material 144.Conductive capping layer 142's bottom surface 141 can cover both layerof conductive material 146's top surface and edge portions of layer ofinsulating material 144's top surface. In some embodiments, conductivecapping layer 142 can have a horizontal (e.g., in the x-direction)extension EXT₁₄₂ over layer of insulating material 144 ranging fromabout 0.1 nm to about 10 nm. Other dimensions of EXT₁₄₂ are within thespirit and scope of this disclosure.

Further, as shown in FIG. 1B, trench conductor layer 162 can be formedthrough layer of insulating material 148 and metallic capping layer 142to physically contact the underlying layer of conductive material 146.For example, trench conductor layer 162 can further include an uppersidewall 163A in contact with layer of insulating material 148, and alower sidewall 163B in contact with metallic capping layer 142. Trenchconductor layer 162's bottom surface 161 between two opposite (e.g., inthe x-direction) lower sidewalls 163B can physically contact layer ofconductive material 146. Since trench conductor layer 162 can be formedthrough metallic capping layer 142 to directly contact the underlyinglayer of conductive material 146 without any intermediate layer inbetween, the contact resistance between layer of conductive material 146and trench conductor layer 162 can be reduced. Accordingly, interconnectstructure 140 can provide a low resistance routing network for FETs 102with alleviated electromigration failure.

In some embodiments, trench conductor layer 162 can physically contactlayer of conductive material 146 with a contact area substantiallyidentical to bottom surface 161's area. In some embodiments, trenchconductor layer 162 can physically contact layer of conductive material146 with a contact area substantially identical to a horizontally (e.g.,parallel to the x-y plane) cross-sectional area A_(163B) between twoopposite lower sidewalls 163B. In some embodiments, trench conductorlayer 162 can physically contact layer of conductive material 146 with acontact area from about 50% to about 100% of cross-sectional areaA_(163B), from about 60% to about 100% of cross-sectional area A_(163B),from about 70% to about 100% of cross-sectional area A_(163B), fromabout 80% to about 100% of cross-sectional area A_(163B), or from about90% to about 100% of cross-sectional area A_(163B). In some embodiments,trench conductor layer 162 can physically contact layer of conductivematerial 146 with a contact area substantially identical to ahorizontally (e.g., parallel to the x-y plane) cross-sectional areaA_(163A) between two opposite upper sidewalls 163A. In some embodiments,trench conductor layer 162 can physically contact layer of conductivematerial 146 with a contact area from about 50% to about 100% ofcross-sectional area A_(163A), from about 60% to about 100% ofcross-sectional area A_(163A), from about 70% to about 100% ofcross-sectional area A_(163A), from about 80% to about 100% ofcross-sectional area A_(163A), or from about 90% to about 100% ofcross-sectional area A_(163A). In some embodiments, upper sidewall 163Acan be a slanted surface, such that cross-sectional area A_(163A) canrange about from about 30% to about 100% to top surface 165's area. Insome embodiments, lower sidewall 163B can be a slanted surface, suchthat cross-sectional area A_(163B) can range about from about 10% toabout 100% to top surface 165's area. In some embodiments, uppersidewall 163A and lower sidewall 163B can be a continuous side surface.In some embodiments, upper sidewall 163A and lower sidewall 163B can belaterally (e.g., in the x-direction) displaced from each other.

In some embodiments, an intermediate layer (not shown in FIG. 1B) can beformed between trench conductor layer 162 and layer of conductormaterial 146 when forming trench conductor layer 162 through metalliccapping layer 142. The intermediate layer (not shown in FIG. 1B) can beformed between a first portion of bottom surface 161 and layer ofconductive material 146, while a second portion of bottom surface 161can physically contact layer of conductive material 146. By way ofexample and not limitation, the intermediate layer can be a residuelayer (e.g., intermixing layer 742 as latter discussed in FIGS. 7A-7B)associated with metallic capping layer 142. For example, theintermediate layer can be a metallic layer that can include halogencompounds, such as a mixture compound of fluorine and metallic cappinglayer 142 or a mixture compound of chlorine and metallic capping layer142. In some embodiments, the intermediate layer can be a layer ofdielectric material, a layer of oxide material, or a layer of insulatingmaterial. A coverage of the intermediate layer over bottom surface 161can be determined by an etching efficiency of the etching process whenforming via 801 (not shown in FIG. 1B; shown in FIG. 8) throughconductive capping layer 142. For bottom surface 161's width W₁₆₁ thatcan range from about 1 nm to about 80 nm, at least 50% of theintermediate layer can be removed by the etching process when formingvia 801. Accordingly, trench conductor layer 162 can contact layer ofconductive material 146 with a contact area greater than about 50%. Insome embodiments, trench conductor layer 162 can partially contact layerof conductive material 146 with a contact area from about 50% to about100% of bottom surface 161's area, from about 60% to about 100% ofbottom surface 161's area, from about 70% to about 100% of bottomsurface 161's area, from about 80% to about 100% of bottom surface 161'sarea, or from about 90% to about 100% of bottom surface 161's area.

FIG. 2 is a flow diagram of an example method 200 for fabricatingsemiconductor device 100, according to some embodiments. Forillustrative purposes, the operations illustrated in FIG. 2 will bedescribed with reference to FIGS. 3A-3B, 4-6, 7A-7C, and 8-10. FIG. 3Ais an isometric view of semiconductor device 100 at various stages ofits fabrication, according to some embodiments. FIGS. 3B, 4-6, 7A-7C,and 8-10 are cross-sectional views along line B-B of FIG. 3A at variousstages of its fabrication to form semiconductor device 100, according tosome embodiments (e.g., semiconductor devices 300-900 of FIGS. 3B, 4-6,7A-7C, 8, and 9 can represent stages of fabrication to formsemiconductor device 100.) Operations can be performed in a differentorder or not performed depending on specific applications. Method 200may not produce a complete semiconductor device 100. Accordingly, it isunderstood that additional processes can be provided before, during, andafter method 200, and that some other processes may only be brieflydescribed herein. Further, the discussion of elements in FIGS. 1A, 1B,3A-3B, 4-6, 7A-7C, and 8-10 with the same annotations applies to eachother, unless mentioned otherwise.

Referring to FIG. 2, in operation 205, a transistor structure with metalcontacts is provided. For example, FIG. 3B shows a semiconductor device300 with one or more FETs 102 having trench conductor layers 130.Referring to FIGS. 3A and 3B, semiconductor device 300 can include finstructure 108 traversed by gate structures 112 and encapsulated by ILDlayer 118 and padding layer 126. By way of example and not limitation,the formation of semiconductor device 300 can include forming finstructure 108 on substrate 106, forming STI region 138 adjacent to finstructure 108, forming gate structure 112 traversing through finstructure 108, forming S/D regions 110, forming ILD layer 118 over aportion of fin structure 108 not covered by gate structure 112, andforming padding layer 126 over gate structure 112 and ILD layer 118. Theformation of semiconductor device 300 can further include forming trenchconductor layer 130 through padding layer 126 and ILD layer 118 tocontact S/D regions 110 and/or gate structure 112. Based on thedisclosure herein, other formation methods for semiconductor device 300are within the spirit and scope of this disclosure.

Referring to FIG. 2, in operation 210, a layer of conductive material isformed over at least one of the metal contacts. For example, as shown inFIG. 4, layer of conductive material 146 can be formed over theunderlying FET 102's trench conductor layer 130. In some embodiments,layer of conductive material 146 can include a wire conductor layer 146Band a barrier liner layer 146A surrounding wire conductor layer 146B'sbottom and sides. By way of example and not limitation, a process forforming layer of conductive material 146 can include (i) forming apatterned layer of insulating material 144 over semiconductor device 300of FIGS. 3A and 3B to expose one or more trench conductor layers 130using a deposition process, a lithography process, and an etchingprocess, (ii) blanket depositing a barrier liner material and aconductive material over the patterned layer of insulating material 144using a deposition process, and (iii) polishing the deposited barrierliner material and the conductive material using a chemical mechanicalpolishing (CMP) process to form layer of conductive material 146 (e.g.,wire conductor layer 146B and barrier liner layer 146A) substantiallycoplanar with layer of insulating material 144. In some embodiments,layer of insulating material 144 can expose a group of trench conductorlayers 130 while covering another group of trench conductor layers 130.In some embodiments, the deposition process for layer of insulatingmaterial 144 can include depositing a dielectric material using chemicalvapor deposition (CVD), plasma enhanced chemical vapor deposition(PECVD), a spin-on process, physical vapor deposition (PVD), or atomiclayer deposition (ALD). By way of example and not limitation, thedielectric material for layer of insulating material 144 can include anysuitable insulating material, such as silicon oxide, silicon nitride,silicon oxynitride, silicate glass, aluminum oxide, hafnium oxide,zirconium oxide, a low-k dielectric, and a high-k dielectric. In someembodiments, the deposition process for barrier liner material and/orthe conductive material can include a CVD process, a PVD process, an ALDprocess, a plating process, or an electroless deposition (ELD) process.By way of example and not limitation, the barrier liner material forlayer of conductive material 146 can include includes a metallicmaterial (e.g., Ta or TiW), a metal oxide (e.g., alumina, manganeseoxide, chromium oxide, niobium oxide, titanium oxide, or combinationsthereof), a metal nitride (e.g. TaN or TiN), a metal compound (e.g.,alumina, manganese oxide, chromium oxide, niobium oxide, titanium oxide,and/or combinations thereof), a carbon-containing material, orcombinations thereof. By way of example and not limitation, theconductive material for layer of conductive material 146 can include Cu,Co, Ni, Ru, Rh, Ir, Os, Al, In, Ag, Au, W, or carbon nanotubes.

Referring to FIG. 2, in operation 215, a conductive capping layer isformed over the layer of conductive material, and a stack of dielectricmaterial is formed over the conductive capping layer. For example, asshown in FIG. 6, conductive capping layer 142 can be formed over layerof conductive material 146, and layer of insulating material 148 can beformed over conductive capping layer 142, as described with reference toFIGS. 5 and 6.

Referring to FIG. 5, a process for forming conductive capping layer 142can include selectively growing one or more conductive materials overlayer of conductive material 146 while exposing adjacent layer ofinsulating material 144 using a selective deposition process. Forexample, the one or more conductive materials can be selectively grownover barrier liner layer 146A and conductor layer 146B. In someembodiments, the one or more conductive materials can be laterallyextended and formed over layer of insulating material 144's edge portionadjacent to layer of conductive material 146 during the growth of theone or more conductive materials. Accordingly, the resulting conducivecapping layer 142 can include upper shoulder structure 152 and lowershoulder structure 154. By way of example and not limitation, the one ormore conductive materials for conductive capping layer 142 can includeCo, W, Ta, TiN, or TaN. In some embodiments, the selective depositionprocess for forming conductive capping layer 142 can include an ALDprocess, a CVD process, a plating process, or an ELD process. Forexample, a CVD process can selectively deposit Co over layer ofconductive material 146 by using an appropriate precursor, such as Ru,that can selectively nucleate over layer of conductive material 146. Theresulting conductive capping layer 142 can fully encapsulate theunderlying layer of conductive material 146 to inhibit theelectromigration associated the underlying layer of conductive material146. In some embodiments, the resulting conductive capping layer 142'sthickness H₁₄₂ can range from about from about 2 nm to about 5 nm. Otherthicknesses of H₁₄₂ are within the spirit and scope of this disclosure.

In some embodiments, a process of selectively forming conductive cappinglayer 142 over layer of conductive material 146 can include (i)selectively forming a layer of inhibitor material (not shown in FIG. 5)over layer of insulating material 144 of semiconductor device 400 ofFIG. 4 using a self-assembly process and (ii) blanket depositing the oneor more conductive material (e.g., Co, W, Ta, TiN, or TaN) using adeposition process, where the deposition process can be delayed orinhibited on the surface of the layer of inhibiting material.Accordingly, the one or more conductive material can be patterned toselectively form conductive capping layer 142 over layer of conductivematerial 146.

Referring to FIG. 6, a process for forming layer of insulating material148 can include sequentially blanket depositing one or more dielectriclayers over semiconductor device 500 of FIG. 5 via a deposition process.For example, as shown in FIG. 6, the deposition process can deposit etchstop layer (ESL) 148A over layer of insulating material 144 andconductive capping layer 142 and deposit a layer of dielectric material148B over ESL 148A. By way of example and not limitation, the depositionprocess for forming layer of insulating material 148 can include a CVDprocess, an ALD process, a PVD process, or a high-density-plasma (HDP)CVD process. Although FIG. 6 illustrates depositing two dielectriclayers (e.g., ESL 148A and layer of dielectric material 148B) to formlayer of insulating material 148, any number of dielectric layers can besequentially deposited to form layer of insulating material 148. In someembodiments, the one or more dielectric layers (e.g., ESL 148A and layerof dielectric material 148B) can have different etching selectivity fromeach other. Accordingly, each of the one or more dielectric layers canhave different thickness based on the etching selectivity between eachother. As such, a thickness ratio between layer of dielectric material148B to ESL 148A (e.g., thickness H_(148B):thickness H_(148A)) can rangefrom about 10 to about 150 based on the etching selectivity in between.In some embodiments, a dielectric layer (e.g., ESL 148A) of the one ormore dielectric layers that physically contacts conductive capping layer142 can encapsulate conductive capping layer 142's top surface 145 andsidewall 143. For example, ESL 148A's thickness H_(148A) can be greaterthan conductive capping layer 142's thickness H₁₄₂ to encapsulate topsurface 145 and side surfaces 143. Each of the one or more dielectriclayers (e.g., ESL 148A and layer of dielectric material 148B) caninclude suitable insulating materials. In some embodiments, a dielectriclayer (e.g., ESL 148A) of the one or more dielectric layers thatphysically contacts conductive capping layer 142 can include a catalystmaterial that can assist an etching process to form intermixing layer742 (e.g., shown in FIGS. 7A-7C) in conductive capping layer 142 atoperation 220. In some embodiments, each of the one or more dielectriclayers for forming layer of insulating material 148 can include thecatalyst material. In some embodiments, the catalyst material caninclude a nitride material, such as aluminum nitride, silicon nitride,nitrogen-doped silicon carbide, silicon carbide, or oxygen-doped siliconcarbide. In some embodiments, each of the one or more dielectric layers(e.g., ESL 148A and layer of dielectric material 148B) can includesilicon oxide, silicon nitride, silicon oxynitride, silicon carbide,silicon carbon nitride, silicon oxycarbide, silicon oxycarbonitride,aluminum oxide, aluminum oxynitride, zirconium oxide, zirconium aluminumoxide, hafnium oxide, a low-k dielectric material, or a high-kdielectric material.

Referring to FIG. 2, in operation 220, a layer of trench conductor isformed through the stack of dielectric material and the conductivecapping layer to contact the layer of conductive material. For example,as shown in FIG. 9, trench conductor layer 162 can be formed throughlayer of insulating material 148 and conductive capping layer 142 tophysically contact layer of conductive material 146, as described withreference to FIGS. 7A-7C, 8, and 9. A process for forming layer oftrench conductor 162 can include (i) forming a patterned hard mask layer772 (shown in FIG. 7A) over semiconductor device 600 of FIG. 6, (ii)forming a via 701 in layer of insulating material 148 (shown in FIG.7A), (iii) forming via 801 with horizontal (e.g., in the x-direction)width W₁₆₁ through conductive capping layer 142 to expose layer ofconductive material 146 (shown in FIG. 8), and (iv) filling one or moreconductive materials in via 801 to form trench conductor layer 162 thatphysically contact layer of conductive material 146.

Referring to FIG. 7A, a process for forming hard mask layer 772 caninclude (i) blanket forming a dielectric material over layer ofinsulating material 148 and (ii) etching the dielectric material througha photoresist layer (not shown in FIG. 7A) patterned by a lithographyprocess. By way of example and not limitation, the dielectric materialfor hard mask layer 772 can include silicon oxide that can be depositedusing any suitable deposition method, such as a CVD process, a PECVDprocess, a PVD process, and an ALD process. In some embodiments, thedielectric material for hard mask layer 772 can be a polymer layer thatcan be formed using a spin-coating method. In some embodiments, theresulting hard mask layer 772 can have a thickness H₇₇₂ ranging fromabout 10 nm to about 50 nm. Based on the disclosure herein, othermaterial and thickness for hard mask layer 772 are within the scope andspirit of this disclosure.

A process for forming via 701 can include etching layer of insulatingmaterial 148 through hard mask layer 772 using an etching process. Insome embodiments, the etching process can remove an upper portion oflayer of insulating material 148 while preserving a lower portion oflayer of insulating material 148. For example, as shown in FIG. 7A, dueto the etching selectivity between layer of dielectric material 148B andESL 148A, the etching process can remove layer of dielectric material148B to form via 701 that can land on ESL 148A. In some embodiments, theetching process can remove layer of insulating material 144 to form via701 with slanted sidewalls. The etching process for forming via 701 caninclude a wet etching process, a dry etching process, or a combinationthereof. In some embodiments, the wet etching process can include usinga diluted hydrofluoric acid (DHF) treatment, an ammonium peroxidemixture (APM), a sulfuric peroxide mixture (SPM), hot deionized water(DI water), tetramethylammonium hydroxide (TMAH), or a combinationthereof. In some embodiments, the dry etching process can include usinga plasma dry etch associated with a gas mixture havingoctafluorocyclobutane (C₄F₈), fluoroform (CHF₃), carbon tetrafluoride(CF₄), difluoromethane (CH₂F₂), argon (Ar), nitrogen (N₂), oxygen (O₂),helium (He), chlorine (Cl₂), hydrogen bromide (HBr), or a combinationthereof. In some embodiments, the resulting via 701 can have ahorizontal (e.g., in the x-direction) width W₇₀₁ ranging from about 1 nmto about 80 nm. Other via 701's widths W₇₀₁ are within the scope andspirit of this disclosure.

Further, as shown in FIG. 7A, the process for forming via 701 can alsoresult in the formation of an intermixing layer 742 in conductivecapping layer 142. Intermixing layer 742 can result from an reactionbetween portions of conductive capping layer 142 under via 701 and theetching process for forming via 701. For example, the etching processfor forming via 701 can include a dry etch using a fluorine-containedplasma that removes layer of dielectric material 148B. Based on thepower and the biased voltage associated with fluorine-contained plasma,the straggle (e.g., standard deviation of plasma's drift and/ordiffusion) of the fluorine-contained plasma can be greater than portionsof ESL 148A above conductive capping layer 142 (e.g.,straggle≥H_(148A)−H₁₄₂). Accordingly, portions of the fluorine-containedplasma can penetrate through ESL 148A to react with conductive cappinglayer 142 to form intermixing layer 742 that includes compounds offluorine and the material of conductive capping layer 142. In someembodiments, conductive capping layer 142 can include Co, where theassociated intermixing layer 742 can include a compound of Co andfluorine (e.g., CoF_(x)). Based on the plasma species associated withthe dry etch process, in some embodiments, intermixing layer 742 caninclude the compound of the material of conductive capping layer 142,chlorine, bromine, carbon, oxygen, sulfur, phosphorus, or nitrogen. Insome embodiments, the plasma straggle of the dry etch process can changecrystallinity of the portions of conductive capping layer 142 under via701. Accordingly, intermixing layer 742 can be an amorphized counterpartof conductive capping layer 142. In some embodiments, the plasmastraggle of the dry etch process can sputter a material from layer ofinsulating material 148, where such sputtered material can be a catalystto convert the underlying conductive capping layer 142 to formintermixing layer 742. For example, ESL 148A can be made of aluminumnitride that can be sputtered by the plasma straggle as a catalyst toform intermixing layer 742. In some embodiments, a bias voltageassociated with the dry etch process can range from about 10 volts toabout 1000 volts to provide the straggle that can penetrate through ESL148A to form intermixing layer 742. In some embodiments, aradio-frequency (RF) power associated with the dry etch process canrange from about 10 Watts to about 1000 Watts to provide the stragglethat can penetrate through ESL 148A to form intermixing layer 742. Insome embodiments, due to the lateral (e.g., along the x-y plane) of thestraggle of the dry etch process, intermixing layer 742 can have ahorizontal (e.g., in the x-direction) width W₇₄₂ greater than via 701'sbottom width W₇₀₁. In some embodiments, intermixing layer 742's widthW₇₄₂ can be substantially identical to via 701's bottom width W₇₀₁.

In some embodiments, the etching process for forming via 701 can etchthrough layer of insulating material 148. Referring to FIG. 7B, theetching process can remove each of ESL 148A and layer of dielectricmaterial 148B. In some embodiments, the etching process can include adry etch process that can further result in intermixing layer 742 undervia 701 as previously discussed. Accordingly, the resulting via 701 canbe formed through layer of insulating material 148 to expose intermixinglayer 742.

In some embodiments, referring to FIG. 7C, after forming via 701 inlayer of insulating material 148, a via 703 can be further formed in via701 with narrower bottom width W₇₀₃ (e.g., width W₇₀₃<width W₇₀₁). Byway of example and not limitation, a process for forming via 703 caninclude (i) forming a photoresist layer (not shown in FIG. 7C) in via701 using a lithography process, and (ii) remove layer of insulatingmaterial 148 through the photoresist using an etching process. In someembodiments, the etching process can include a dry etch process that canfurther form intermixing layer 742 under via 703 as previouslydiscussed.

Referring to FIG. 8, a process for forming via 801 can includeselectively removing intermixing layer 742 from conductive capping layer142 using an etching process. In some embodiments, prior to the removalof intermixing layer 742, the process for forming via 801 can furtherinclude removing portions of layer of insulating material 148 under via701 using the etching process. The etching process for forming via 801can include a wet etching process, a dry etching process, or acombination thereof. The wet etching process can include using wetetchants that can dissolve intermixing layer 742. In some embodiments,the wet etchants can include an oxidizer, such as hydrogen peroxide. Insome embodiments, a concentration of hydrogen peroxide can be from about0.5% to about 8%. If the concentration is greater than 8%, it canincrease difficulty to control the oxidation reaction. If theconcentration is smaller than 0.5%, it can be insufficient to remove theintermixing layer. For example, intermixing layer 742 can include acompound of fluorine and cobalt (e.g., CoF_(x)), where the wet etchingprocess can use hydrogen peroxide to dissolve the CoF_(x) compound(e.g., intermixing layer 742) to form via 801 to expose the underlyinglayer of conductive material 146 (e.g., metal layer 146B). In someembodiments, the oxidizer for the wet etching process can furtherinclude nitric acid, sulfuric acid, bromine, or any other suitableoxidizer agents. In some embodiments, the wet etching process forforming via 801 can also include using DI water to dissolve intermixinglayer 742. In some embodiments, the wet etching process for forming via801 can further include using a DHF treatment, an APM treatment, a SPMtreatment, or a combination thereof. The dry etching process for formingvia 801 can include using a plasma dry etch associated with a gasmixture having C₄F₈, CHF₃, CF₄, CH₂F₂, Ar, N₂, O₂, O₃, He, Cl₂, or HBr.

In some embodiments, prior to removing intermixing layer 742, theprocess for forming via 801 can further include a dechuck process toenhance an etching efficiency of the etching process that removesintermixing layer 742. In some embodiments, the dechuck process canremove electrostatic charges on semiconductor device 700 (shown in FIGS.7A-7C), and therefore can alter surface hydrophobicity of via 701.Accordingly, the etchant (e.g., hydrogen peroxide) of the etchingprocess for removing intermixing layer 742 can be more efficientlytransported through via 701 to react with intermixing layer 742. Thedechuck process can be performed using a low density plasma. By way ofexample and not limitation, the low density plasma for the dechuckprocess can be generated under a pressure from about 3 mTorr to about200 mTorr. In some embodiments, the low density plasma for the dechuckprocess can be generated at a power from about 10 Watts to about 1000Watts. If the power is greater than 1000 Watts, it can introducephysical damage on semiconductor device 700 (shown in FIGS. 7A-7C). Ifthe power is less than 10 Watts, it is insufficient to remove theelectrostatic charge to alter surface hydrophobicity of via 701. Basedon the disclosure herein, other methods for performing dechuck processmay be within the spirit and scope of this disclosure.

Referring to FIG. 9, the filling of one or more conductive materiallayers can include (i) blanket depositing the one or more conductivematerial layers using a deposition process, and (ii) polishing thedeposited one or more conductive material layers using a CMP process toform trench conductor layer 162 substantially coplanar with layer ofinsulating material 148. In some embodiments, the one or more conductivematerial layers can include a barrier liner layer 962A and a viaconductor layer 962B. By way of example and not limitation, barrierliner layer 962A can include a metallic material (e.g., Ta or TiW), ametal oxide (e.g., alumina, manganese oxide, chromium oxide, niobiumoxide, titanium oxide, or combinations thereof), a metal nitride (e.g.TaN or TiN), a metal compound (e.g., alumina, manganese oxide, chromiumoxide, niobium oxide, titanium oxide, and/or combinations thereof), acarbon containing material, or combinations thereof. By way of exampleand not limitation, via conductor layer 962B can include Cu, Co, Ni, Ru,Rh, Ir, Os, Al, In, Ag, Au, W, or carbon nanotubes. In some embodiments,the deposition process for barrier liner layer 962A and via conductorlayer 962B can include a CVD process, a PVD process, an ALD process, aplating process, or an ELD process.

Referring to FIG. 2, in operation 225, another layer of conductivematerial can be formed over the layer of trench conductor. For example,as shown in FIG. 10, interconnect structure 140 ₂'s layer of conductivematerial 146 can be formed over trench conductor layer 162 and layer ofinsulating material 148. A process for forming interconnect structure140 ₂'s layer of conductive material 146 can be similar to operation 210as previously described. For example, the process for forminginterconnect structure 140 ₂ can include (i) blanket depositing one ormore dielectric layers (e.g., interconnect structure 140 ₂'s layer ofinsulating material 148) over semiconductor device 900 of FIG. 9 via asuitable deposition process, such as a CVD process, a PECVD process, aPVD process, and an ALD process, (ii) forming a via (not shown in FIG.10) through the deposited dielectric layers to expose layer ofinterconnect structure 140 ₁'s layer of conductive material 146 using alithography process and an etching process, (iii) filling the via withone or more conductive materials, and polishing the one or moreconductive materials using a CMP process.

Further, in operation 225, other components of interconnect structure140 ₂, such as interconnect structure 140 ₂'s conductive capping layer142, trench conductor layer 162, and layer of insulating material 148can be formed over interconnect structure 140 ₂'s layer of conductivematerial 146 using similar fabrication steps as previously described inoperations 210, 215, and 220.

The present disclosure provides an exemplary interconnect structure anda method for forming the same. The interconnect structure can include aconductive wire layer, a layer of insulating material over theconductive wire layer, and a conductive capping layer embedded in thelayer of insulating material and over the conductive wire layer. Theinterconnect structure can further include a trench conductor layerformed through the layer of insulating material and the conductivecapping layer to physically contact the conductive wire layer. In someembodiments, the method of forming the trench conductor layer throughthe layer of insulating material and the conductive capping layer caninclude converting portions of the conductive capping layer to afluorine-contained compound, removing the fluorine-contained compound toform a via through the conductive capping layer, and filling the viawith one or more conductive materials. The interconnect structure canprovide the benefit of a low resistance routing network while avoidingelectromigration failure, thus enhancing performance and yield of theintegrated circuit.

In some embodiments, a method for forming an interconnect structure caninclude forming a layer of conductive material over a substrate, forminga metallic capping layer over the layer of conductive material, forminga layer of insulating material over the metallic capping layer, forminga via within the layer of insulating material and the metallic cappinglayer, and filling the via with an other layer of conductive material.

In some embodiments, a method for forming an interconnect structure caninclude forming a fin structure on a substrate, forming a metal contactover the fin structure, forming a layer of conductive material over themetal contact, forming a metallic capping layer over the layer ofconductive material, forming a layer of insulating material over themetallic capping layer, and forming a via in the layer of insulatingmaterial and the metallic capping layer to expose the layer ofconductive material.

In some embodiments, an interconnect structure can include a substrate,a layer of conductive material over the substrate, a metallic cappinglayer over the layer of conductive material, a layer of insulatingmaterial over top and side surfaces of the metallic capping layer, and alayer of trench conductor formed in the layer of insulating material andthe metallic capping layer.

The foregoing disclosure outlines features of several embodiments sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodimentsintroduced herein. Those skilled in the art should also realize thatsuch equivalent constructions do not depart from the spirit and scope ofthe present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A method for forming an interconnect structure,comprising: forming a first layer of conductive material over asubstrate; forming a first layer of insulating material substantiallycoplanar with the first layer of conductive material; forming a metalliccapping layer by selectively growing the metallic capping layer over thefirst layer of conductive material while exposing the first layer ofinsulating material; forming a second layer of insulating material overthe metallic capping layer; forming a via opening through the secondlayer of insulating material and the metallic capping layer; and fillingthe via opening with a second layer of conductive material.
 2. Themethod of claim 1, wherein forming the metallic capping layer comprisesselectively growing one or more of cobalt, ruthenium, tungsten, andcombinations thereof over the first layer of conductive material.
 3. Themethod of claim 1, wherein forming the second layer of insulatingmaterial comprises depositing the second layer of insulating materialover a top surface and a side surface of the metallic capping layer. 4.The method of claim 1, wherein forming the second, layer of insulatingmaterial comprises depositing an aluminum nitride layer over themetallic capping layer, and wherein forming the via opening comprises:sputtering the aluminum nitride layer to form a catalyst; catalyzing, bythe catalyst, a formation of an intermixing layer within the metalliccapping layer; and removing the intermixing layer.
 5. The method ofclaim 1, wherein forming the via opening comprises: forming a layer ofhalogen-containing compounds within the metallic capping layer; andremoving the layer of halogen-containing compounds with an oxidizer. 6.The method of claim 1, wherein forming the via opening comprisesremoving electrostatic charges in the via opening with a dechuck processassociated with a power between about 10 Watts and about 1000 Watts. 7.A method for forming an interconnect structure, comprising: forming atransistor structure on a substrate; forming a metal contact over thetransistor structure; forming a layer of conductive material over themetal contact; forming a metallic capping layer over the layer ofconductive material; forming a layer of insulating material over themetallic capping layer; forming a via opening through the layer ofinsulating material and the metallic capping layer to expose the layerof conductive material; and forming a barrier liner layer to contact thelayer of conductive material and the metallic capping layer.
 8. Themethod of claim 7, further comprising forming an other layer ofinsulating material over the transistor structure, wherein forming themetallic capping layer comprises selectively growing the metalliccapping layer over the layer of conductive material while exposing theother layer of insulating material.
 9. The method of claim 7, whereinforming the layer of insulating material comprises depositing the layerof insulating material over a top surface and a side surface of themetallic capping layer.
 10. The method of claim 7, wherein forming thevia opening comprises: forming the via opening in the layer ofinsulating material and over a portion of the metallic capping layer;and intermixing the portion of the metallic capping layer with one ormore of fluorine, chlorine, bromine, carbon, oxygen, sulfur, phosphorus,nitrogen, and combinations thereof.
 11. The method of claim 10, whereinforming the via opening further comprises removing the portion of themetallic capping layer with an oxidizer.
 12. The method of claim 7,wherein the barrier liner layer comprises one or more of a metal, ametal oxide, a metal compound, a carbon-containing material, andcombinations thereof.
 13. A method, comprising: forming a metalliccapping layer over a first conductive layer; depositing an insulatinglayer on the metallic capping layer; removing a portion of theinsulating layer with an etching process to expose a portion of themetallic capping layer; reacting the portion of the metallic cappinglayer with the etching process to form an intermixing layer whilecatalyzing the formation of the intermixing layer with a sputteredmaterial of the insulating layer; removing the intermixing layer to forman opening, wherein the opening is through the insulating layer and themetallic capping layer; and forming a second conductive layer in theopening and in contact with the first conductive layer.
 14. The methodof claim 13, wherein the etching process comprises a dry etch processusing a halogen-containing plasma, and wherein reacting the portion ofthe metallic capping layer comprises: penetrating the halogen-containingplasma through the metallic capping layer; and forming the intermixinglayer with a halogen of the halogen-containing plasma and a material ofthe metallic capping layer.
 15. The method of claim 13, wherein reactingthe portion of the metallic capping layer comprises forming anamorphized material of a crystalline material of the metallic cappinglayer.
 16. The method of claim 1, wherein forming the metallic cappinglayer comprises extending the metallic capping layer over an edge of thefirst layer of conductive material.
 17. The method of claim 1, whereinforming the metallic capping layer comprises selectively forming a layerof inhibitor over the first layer of insulating material.
 18. The methodof claim 14, wherein depositing the insulating layer comprisesdepositing an etch stop layer (ESL) over the metallic capping layer, andwherein reacting the portion of the metallic capping layer furthercomprises penetrating the halogen-containing plasma through the ESL. 19.The method of claim 1, further comprising forming a barrier liner layerin the via opening to contact the first layer of conductive material andthe metallic capping layer.
 20. The method of claim 13, furthercomprising forming a barrier liner layer in the opening to contact themetallic capping layer.